1. Field of the Invention
The present invention relates to phosphors, a method for manufacturing the same, and a display device and a fluorescent lamp that use the phosphors, and more particularly to alkaline-earth metal aluminate phosphors and a method for manufacturing the same.
2. Related Art
In recent years, phosphors having Eu (europium) as a luminescence center have been applied as low energy phosphors for plasma display panels (PDPs), 3-wavelength fluorescent lamps, and the like.
The following compositions are given here as specific examples of such phosphors: (Y,Gd)BO3:Eu, Y2O2S:Eu, Y2O3:Eu, BaMgAl10O17:Eu, CaAl2O4:Eu, CaMgSi2O6:Eu, SrAl14O25:Eu, Sr2P2O7:Eu, (Sr,Ca)B4O7:Eu, Ca2B5O9Cl:Eu, Ba0.75Al10O17.25:Eu, (Sr,Ca,Ba,Mg)10(PO4)6Cl2:Eu, InBO3:Eu, (BaMg)Si2O5:Eu, YAl3(BO3)4:Eu, LaAlO3:Eu
(For a detailed description of phosphor compositions see, for example, Phosphor Handbook by Shigeo Shionoya and William M. Yen (CRC Press, 1999, pp. 392/833), and Japanese published patent applications No. 8-31325, No. 60-115683, No. 2001-55567 and No. 2001-35372.)
The emission color of these phosphors is adjusted by combining them with different colored phosphors, so as to achieve white luminescence, for example.
Of the above compositions, BaMgAl10O17:Eu phosphors have recently been widely applied in PDPs (i.e. type of gas discharge display panel), mercury-free fluorescent lamps and the like, making use of the superior visible luminescence characteristics of these phosphors under vacuum ultraviolet (VUV) excitation.
With PDPs, slurry made by mixing binder with phosphors is applied to a substrate (e.g. glass) and baked to form a phosphor screen consisting of phosphor layers.
Eu atoms are used as the luminescence center of these phosphor compositions, although the generally high cost of Eu raw material makes it desirable to minimize the amount of Eu used in the interests of reducing manufacturing costs.
Simply decreasing Eu, however, will likely have an adverse effect on the luminescence characteristics, since this equates to a reduction in the luminescence center material included in the phosphors.